Related Party Transactions (Other Related Party Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Prepaid expenses and other current assets	$ 10	$ 20
Other assets	52	5
Deferred revenues	16	60
Other current liabilities	3	5
Other liabilities	94	42
Phillips 66
Related Party Transaction [Line Items]
Prepaid expenses and other current assets	7	4
Other assets	44	0
Deferred revenues	16	60
Other current liabilities	1	0
Other liabilities	$ 70	$ 18